The above referenced patent discloses a method and apparatus for the production and treatment of gases. In this same patent, a disclosure is made of a novel gasifier adapted for the continuous flow of slag from an orifice disposed to the bottom of the gasifier. FIGS. 3 and 5 accompanying the above referenced patent illustrate this slagging gasifier.
The present invention relates to gasifiers which gasify materials that contain ash, such as coal, trash, tires, etc. but in particular to gasifiers that gasify such materials and convert their residue to a molten slag, as for example the gasifiers described in U.S. Pat. Nos. 4,129,422 and 4,195,978. These referenced patents possess a slag removal, high thermal conductive metallic orifice which is centrally located in the bottom of the gasifier and through which orifice a liquid coolant circulates in order to prevent this metallic orifice from melting or distorting. The said orifice is adapted to have hot burner gases directed up through the bore of the orifice itself in order to have the gases retain the slag in molten condition on the hearth or bottom of the gasifier and to maintain a pool of slag above said orifice or said hearth. Periodically the slag is discharged through the liquid-cooled metallic orifice by stopping or reducing the burner gases output and by reducing the pressure in the quenching chamber located below the orifice by controlled venting to the atmosphere through a venting system so as to produce a differential pressure between the quenching chamber and the gasifier vessel (par. 1, col. 1 of U.S. Pat. No. 4,129,422 and par. 2 , col. 1 of 4,195,978), thereby providing an intermittent-flowing slagging gasifier. The disadvantages of such gasifiers are as follows:
1. That a pressure differential between the hearth of the gasifier and the quenching chamber must be provided to cause the slag to flow.
2. That a pool of slag is made to form at the hearth.
During the formation of such pool, the separation of the iron component in the slag from the silicates and aluminates takes place by virture of the iron being the heaviest. This iron tends to solidify at the orifice much quicker than if the iron component had not separated from the slag. In order to prevent such solidification, hot burner gases are directed up through the bore of the orifice in order to maintain the slag above the orifice in molten state and to cause the buildup of a molten pool of slag.
3. The system is much too complex structurally by virtue of having a metallic orifice in a critical area that possesses passages for a coolant in an environment that is difficult to maintain.
4. The referenced system cited is too costly.
Attempts have been made to provide a slagging gasifier with an orifice which is devoid of circulating coolant features and devoid of features for directing hot burner gases up through said orifice. However, since the outlet of the orifice is adjacent to the quenching chamber, excessive heat loss takes place causing the slag to form icicles (stalactites) which ultimately plug the orifice and interrupt the flow of the slag.